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When a machine stalls, a valve fails to return, or a jig loses its clamping force, the culprit is often an undersized or worn-out compression spring. Engineers, CNC builders, and automation hobbyists who need a dependable, dimensionally consistent coil spring for load-bearing applications will find this 120mm compression spring series purpose-built for the task.
Each spring in this series features a coiled steel wire construction with a free length of 120mm (approximately 4.72 in). Wire diameters range from 2mm to 12mm (0.08–0.47 in), and outer diameters span 12mm to 70mm (0.47–2.76 in), covering a wide range of spring rates and load capacities. The close-wound coil geometry ensures consistent pitch and stable axial compression across the full deflection range.
Typical use cases include CNC router Z-axis return mechanisms, pneumatic valve spring replacements, robotic gripper preload assemblies, and industrial jig clamping fixtures — all applications where a reliable 120mm compression coil spring with a defined outer diameter is critical to repeatable performance.
Consistent 120mm (4.72 in) free length across all variants ensures predictable deflection and easy drop-in replacement in existing spring pockets.
Outer diameters from 12mm to 70mm (0.47–2.76 in) and wire diameters from 2mm to 12mm (0.08–0.47 in) cover light-duty to heavy-duty load requirements in a single product family.
Close-wound coil geometry maintains consistent pitch under load, reducing lateral buckling and ensuring straight-line compression throughout the deflection stroke.
Available in packs of 1, 2, or 5 pieces per variant, letting you order exactly what your project or production run requires without excess inventory.
Wound from steel wire with sufficient tensile strength for general mechanical and automation applications. Suitable for indoor and enclosed-environment use cases.
Designed for CNC machines, robotic assemblies, valve return mechanisms, jig fixtures, and DIY automation projects where a compact, defined-length compression spring is required.
| Spring Type | Compression (coil) |
|---|---|
| Free Length | 120 mm (4.72 in) |
| Wire Diameter | 2 mm / 2.5 mm / 3.5 mm / 4.5 mm / 5 mm / 10 mm / 12 mm |
| Outer Diameter | 12 mm – 70 mm (0.47 – 2.76 in) |
| Coil Direction | Right-hand wound |
| End Type | See variant options |
| Material | Steel wire |
| Surface Finish | See variant options |
| Spring Rate | See variant options |
| Max Load Capacity | See variant options |
| Pack Quantity | 1 pc / 2 pcs / 5 pcs (see variant options) |
| Application | CNC, robotics, automation, valve return, jig fixtures |
Measure the bore or spring seat in your assembly. The spring's outer diameter should be slightly smaller than the bore to allow free movement without binding. For a guide rod setup, the inner diameter of the spring (outer diameter minus twice the wire diameter) must clear the rod. Check both clearances before selecting your variant.
Heavier wire diameters produce stiffer springs with higher load capacity. For light-duty return or preload applications (e.g., small valves or sensor arms), 2–2.5mm wire is typically sufficient. For CNC axis return or clamping fixtures under moderate load, 3.5–5mm wire is more appropriate. For heavy industrial loads, consider the 10mm or 12mm wire variants. If you have a specific load and deflection requirement, contact us to confirm.
These springs are wound from standard steel wire and are best suited for indoor, enclosed, or dry environments. For applications exposed to moisture, chemicals, or salt air, consider adding a protective coating or using stainless steel springs. Contact us if you need corrosion-resistant variants for your specific environment.
Yes, provided the free length (120mm), outer diameter, and wire diameter match your existing spring's specifications. Measure your current spring's free length, outer diameter, and wire diameter, then select the matching variant. If your original spring has a different free length, this series will not be a direct drop-in replacement.
The pack quantity (1, 2, or 5 pieces) refers to the number of identical springs included in a single order of that variant. Smaller packs suit prototyping or single-machine repairs; larger packs are more economical for production runs or stocking spare parts. The spring specifications are identical regardless of pack size.
Spring rate (k) is determined by wire diameter, outer diameter, number of active coils, and material modulus. For a precise spring rate value for a specific variant, contact us with your selected wire diameter and outer diameter. As a general guide, larger wire diameters and smaller outer diameters produce higher spring rates (stiffer springs), while smaller wire diameters and larger outer diameters produce lower spring rates (softer springs).
Yes. The 120mm free length and range of outer diameters make these springs well-suited for CNC router Z-axis return, bed-leveling preload, and similar motion-control applications. Select the outer diameter that fits your spring seat and the wire diameter that provides the preload force your design requires. For 3D printer bed leveling, 2–2.5mm wire with a 12–20mm outer diameter is a common starting point.
